Thermocouple Shutoff for Portable Heater

ABSTRACT

Provided is an assembly comprising a combustion-powered heater, a target component, and a transducer operatively engaged with said target component. A combustion-powered heater may comprise a combustion site adapted to power said heater. A target component may be engaged with the combustion site. A transducer may be adapted to measure the temperature of the target component and adapted to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.

The following application is incorporated by reference, in its entirety: International Application No. PCT/US2007/007426, filed Mar. 26, 2007, titled “Gas-Fired Portable Unvented Infrared Heater”, which PCT application claimed priority to U.S. Provisional Application No. 60/743,757, filed Mar. 24, 2006.

TECHNICAL FIELD

Provided is a device for shut-off of a portable heater. More particularly, provided is device to shut down a portable heater in response to certain atmospheric conditions.

BACKGROUND

Combustion-powered heaters combust reactants to yield heat and reaction products. Combustion-powered heaters consume a fuel and an oxidant and react the fuel and oxidant to yield heat and one or more combustion products. Some combustion-powered heaters modify the composition of the local atmosphere by uptake of one or more reactants from the local atmosphere or release of one or more combustion products into the local atmosphere or both.

In some combustion-powered heaters, the combustion process consumes oxygen from the local atmosphere as a combustion reactant. The consumption of oxygen by a combustion-powered heater can modify the composition of the local atmosphere by reducing the local oxygen amounts. In some amounts, reduced local oxygen may be undesirable. It remains desirable to develop technology to detect and address atmospheric conditions such as undesirable amounts of local oxygen.

Some combustion-powered heaters release of one or more combustion products into the local atmosphere. The combustion products may comprise, but are not limited to, carbon dioxide, carbon monoxide, and nitrogen oxides. The release of combustion products can modify the composition of the local atmosphere by increasing the amounts of combustion products therein. In some amounts, the presence of one or more combustion products may be undesirable. It remains desirable to develop technology to detect and address atmospheric conditions such as undesirable amounts of combustion products in the local atmosphere.

SUMMARY

Provided is an assembly comprising a combustion-powered heater, a target component, and a transducer operatively engaged with said target component. A combustion-powered heater may comprise a combustion site adapted to power said heater. A target component may be engaged with the combustion site. A transducer may be adapted to measure the temperature of the target component and adapted to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.

Further provided is a method of selectively shutting off a combustion-powered portable heater. The method may comprise providing a combustion-powered heater. The heater may comprise a combustion site adapted to power said heater when in operation. The method may further comprise engaging a target component with said combustion site in such a manner that said combustion site heats said target component when in operation. The method may further comprise operatively engaging a transducer with said target component. The transducer may be adapted to measure the temperature of the target component, and adapted to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.

Further provided is an assembly comprising a portable, combustion-powered heater, a radiant surface, and at least one thermocouple. The heater may comprise a combustion site adapted to power said heater. The heater may be adapted to consume oxygen from air and propane fuel. The radiant surface may be engaged with the combustion site. The thermocouple may be embedded within the radiant surface. The thermocouple may be adapted to measure the temperature of the radiant surface. The thermocouple may be adapted to cease holding open a normally-closed valve to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.

BRIEF DESCRIPTION OF THE DRAWINGS

The present subject matter may take physical form in certain parts and arrangement of parts, embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof, and wherein:

FIG. 1 is a perspective cross-sectional view of one embodiment of a heater assembly;

FIG. 2 is a longitudinal cross-sectional view of one embodiment of a heater assembly;

FIG. 3 is sectional view of one embodiment of a heater assembly;

FIG. 4 is detail view of one embodiment of a transducer in a heater assembly.

DETAILED DESCRIPTION

Reference will be made to the drawings, FIGS. 1-4, wherein the showings are only for purposes of illustrating certain embodiments of a thermocouple shutoff for portable heater, and not for purposes of limiting the same. Specific characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

Portable heaters may be combustion-powered. Combustion-powered portable heaters 100 are adapted to react fuel, and an oxidant at a combustion site. A combustion site may be any region adapted for conducting a combustion reaction. Without limitation, a combustion site may comprise a burner, or a catalytic surface.

A burner is a device adapted to generate a flame by combustion. In operation, a burner accepts a fuel and an oxidant, combusts the fuel and the oxidant, and outputs heat and a combustion product.

In some embodiments, a burner may be operatively associated with components adapted to modify the output from the burner. Without limitation, a burner output modifier may be adapted to affect the efficiency of the heater, may be adapted to affect the rate of heat output, may be adapted to separate a flow of heat from a flow of combustion products, or may be adapted to focus or disperse a flow of heat. Without limitation, a burner output modifier may include a heat reflector, a heat concentrator, a heat diffuser, a chimney, a heat exchanger, a regenerator, or a radiant surface.

In some embodiments, a burner may produce a naked flame exposed to the environment. Without limitation, a heater comprising a burner adapted to produce a naked flame exposed to the environment will be referred to herein as a blue flame heater unless otherwise noted. In some embodiments a burner may be operatively engaged with a radiant surface adapted to shield the flame from the environment. Without limitation, a radiant heater is one embodiment of heater comprising a burner operatively engaged with a radiant surface adapted to shield the flame from the environment.

A catalytic surface is a combustion site adapted so that a fuel and an oxidant may react thereupon in catalyzed reaction to yield heat and a combustion product. Without limitation, the material of the catalytic surface may act as a catalyst in a catalyzed combustion reaction at the combustion site. Without limitation, a catalyst in a combustion reaction may catalyze the combustion reaction by speeding up the reaction, slowing down the reaction, lowering the ignition energy needed to initiate the combustion reaction, promoting more complete combustion, promoting cleaner combustion, reducing or eliminating certain combustion products, or increasing operating efficiency.

Without limitation, some catalytic surfaces comprise a catalyst supported by a substrate. In certain embodiments a catalyst may comprise ruthenium, rhodium, palladium, osmium, iridium, platinum, and mixtures thereof. Substrates may comprise a glass fiber, a porous metal, a ceramic, or a mixture thereof.

Without limitation, some fuels that a combustion site may react comprise, methane, ethane, propane, butane, pentane, other alkanes, alkenes, alkynes, kerosene, LP gas, wood gas, other gas mixtures, oil, hydrogen, or mixtures thereof. Without limitation, some oxidants that a combustion site may react comprise oxygen, gas mixtures comprising oxygen, nitrous oxide, or mixtures thereof. Without limitation, air is a gas mixture comprising oxygen that may be used as an oxidant.

FIG. 1 shows a combustion-powered portable heater 100. Without limitation, the cross-sectional view also shows a device 80 adapted to shut off a combustion-powered portable heater 100.

FIG. 2 shows a combustion-powered portable heater 100. Without limitations, the cross-sectional view also shows a device 80 adapted to shut off a combustion-powered portable heater 100.

FIG. 3 shows a combustion-powered heater 10. Without limitation, the sectional view shows a fuel control valve 20 adapted to selectively permit fuel flow to a combustion site 40. During operation of heater 10, air flows into heater 10 from the atmosphere 90. In the non-limiting embodiment showing in FIG. 3, the heater 10 comprises intake apertures 80 to admit air into the heater 10. During operation, air and fuel undergo a combustion reaction at combustion site 40 to produce heat and combustion products. The non-limiting embodiment of a combustion site 40 shown in FIG. 3 is a burner 41. By contrast, in other non-limiting embodiments, combustion site 40 may comprise a catalytic surface. Burner 41 comprises an inlet (not shown) for accepting air. The non-limiting embodiment shown in FIGS. 3 and 4 also comprises a burner output modifier 60. Without limitation, burner output modifier 60 comprises a radiant surface 61. Without limitation, the combustion-powered heater 10 shown in FIGS. 3 and 4 also comprises a transducer 50 in engagement with a component of heater 10. The transducer 50 is adapted to detect the temperature of components with which it is engaged. In the non-limiting embodiment shown in FIG. 3, the transducer 50 comprises at least one thermocouple 51, engaged with, and adapted to detect the temperature of, radiant surface 61.

In certain embodiments, the composition of the atmosphere can substantially affect the combustion reaction during operation. “Good air” is a description of air quality. Good air is air from an atmosphere that has not been modified to contain an defined reduced oxygen content or to contain a defined amount of combustion products. The defined reduced oxygen content and the defined amount of combustion products are quantities that may be determined based on engineering judgment. In certain embodiments, during operations in good air, the combustion reaction may be substantially complete. In certain embodiments, during operations in good air, the combustion reaction will produce heat at some rate for a given fuel consumption rate. “Bad air” is another description of air quality. Bad air is air from an atmosphere that has been modified to contain a defined reduced oxygen content or to contain a defined amount of combustion products. In certain embodiments, during operations in bad air, the combustion reaction may be substantially incomplete. In certain embodiments, during operations in bad air the combustion reaction will produce heat at some rate for a given fuel consumption rate; wherein said rate of heat production in bad air is substantially less than the rate of heat production in good air for the same fuel consumption rate.

In some embodiments, because of predictable differences between the rate of heat produced by combustion in good air and the amount of heat produced by combustion in bad air, a transducer 50 sensitive to temperature may be used to detect changes in combustion related to changes local air quality and, thereby, used as a detector of atmospheric quality in terms of good air versus bad air. Such temperature detection may be performed by sensing of the temperature at the combustion site, or by sensing temperature of materials or components engaged with the combustion site 40. That is, a transducer 50 may be used to discriminate between heater operations within good air and burner or heater operations within bad air by measuring the temperature of heater components heated by heat produced at a combustion site 40.

Without limitation a transducer 50 may be electrical or mechanical. A transducer 50 may comprise at least one thermocouple 51, a thermoelectric material, a thermostat, a bi-metallic strip, or a pyrometer.

In some embodiments, and without limitation, operating temperature data of components or materials of the heater 10, can be used to determine air quality. In certain embodiments, operating temperature data of components other than those components in a combustion site 40 can be used to determine air quality. In some embodiments, a transducer 50 is used to take operating temperature data of components of the heater 10 or to acquire a signal representative of operating temperature data of components of the heater 10. Components of the heater 10 from which a transducer 50 is used to take operating temperature data or to acquire a signal representative of operating temperature data are target components 62. Target components 62 may include a burner output modifier 60, a radiant surface 61, or any other component of the heater 10 or material within the heater 10 other than a combustion site 40, a burner 41, a catalytic surface (not shown), or a flame (not shown).

In certain embodiments, operation of a combustion-powered heater 10 in good air may result in an operating temperature of target components or materials 62 at or above some predetermined temperature. Without limitation, in certain embodiments, operation of a combustion-powered heater in bad air may result in an operating temperature of the target components or materials 62 below some predetermined temperature.

In certain embodiments, a transducer 50 comprises at least one thermocouple 51. During operation in good air, the combustion site 40 produces heat sufficient to heat a target component or material 62 to a temperature high enough to produce an output signal consistent with good air from at least one thermocouple 51. During operation in bad air, the combustion site 40 does not produce heat sufficient to heat a target component or material 62 to a temperature high enough to produce an output signal consistent with good air from at least one thermocouple 51.

In certain embodiments, failure of at least one transducer 50 or thermocouple 51 to produce an output signal consistent with good air will trigger an alarm or will trigger actions to stop operations at combustion site 40 or heater 10. In certain embodiments, actions to stop operations at combustion site 40 includes shut off of the valve 20 to interrupt fuel flow necessary to continuing operations at combustion site 40.

In certain embodiments, the heat from combustion site 40 may affect objects and materials in contact engaged with combustion site 40. In certain embodiments, heat from combustion site 40 will propagate through components and materials from areas proximate to or in contact with combustion site 40 to areas more distal from combustion site 40.

Experiment:

As shown in TABLE 1, nine experiments were performed on heater embodiments similar to those shown in FIGS. 3-4. In each experiment at least one thermocouple 51 was engaged with, and provided a potential substantially proportionate to the temperature of, a radiant surface 61. In each experiment, the cut-off potential in the thermocouple in millivolts was established as “TC mV @ Cut-Off”. A potential in the thermocouple of the cut-off potential or less would fail to hold open a fuel control valve 20 and would allow the fuel control valve 20 to close, thereby cutting off fuel to the combustion site 40 and shutting down the heater 10. In each experiment the heater 10 was started and the initial potential in the thermocouple 51 in millivolts was recorded as “Starting Thermocouple (mV)”. The heater 10 was then isolated from the greater atmosphere by sealing it in a small, substantially air-tight, enclosure with a small amount of air. In each experiment, the percentage of oxygen in the air in the enclosure was monitored. Over time, the percentage of oxygen in the air in the enclosure diminished. Over time, the potential in the thermocouple 51 in millivolts diminished. In each experiment, the heater 10 was allowed to operate until the potential in the thermocouple 51 in millivolts diminished to the cut-off potential and the heater 10 shut down. In each experiment, the percentage of oxygen in the air in the enclosure when the heater 10 shut down was recorded as “%O2 Cut-Off”.

Without wishing to be bound to any particular theory, the data in TABLE 1 is consistent with the conclusion that heat produced at a combustion site 40 is a function of the air quality of the atmosphere 90. The operating temperature data of the components of the heater 10 with which thermocouple 51 was engaged produced an output potential consistent with the components dropping in temperature as the air quality in the enclosure decreased. The data is consistent with a finding that the potential in thermocouple 51 is a function of air quality. The results of the experiments are shown in TABLE 1 below.

TABLE 1 Starting Test Number Thermocouple (mV) % O2 Cut-Off TC mV @ Cut-Off 1 20.0 17.88 7.50 2 20.0 17.89 8.00 3 21.0 17.85 8.00 4 20.0 18.00 7.00 5 20.0 17.82 7.50 6 20.0 17.89 7.50 7 20.5 17.99 7.00 8 20.5 17.89 7.00 9 20.0 18.00 8.00

While the thermocouple shutoff for a portable heater has been described above in connection with the certain embodiments, it is to be understood that other embodiments may be used or modifications and additions may be made to the described embodiments for performing the same function of the thermocouple shutoff for a portable heater without deviating therefrom. Further, the thermocouple shutoff for a portable heater may include embodiments disclosed but not described in exacting detail. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments may be combined to provide the desired characteristics. Variations can be made by one having ordinary skill in the art without departing from the spirit and scope of the thermocouple shutoff for a portable heater. Therefore, the thermocouple shutoff for a portable heater should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the attached claims. 

1. An assembly comprising: a combustion-powered heater comprising a combustion site adapted to power said heater; a target component engaged with said combustion site; and a transducer operatively engaged with said target component, said transducer, adapted to measure the temperature of the target component, and adapted to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.
 2. The assembly of claim 1, wherein said heater is portable.
 3. The assembly of claim 2, wherein said heater is adapted to consume oxygen from air and propane fuel.
 4. The assembly of claim 3, wherein said target component comprises a burner output modifier.
 5. The assembly of claim 4, wherein said operative engagement of the transducer with said burner output modifier comprises embedding said transducer within said burner output modifier.
 6. The assembly of claim 5, wherein said burner output modifier comprises a radiant surface.
 7. The assembly of claim 6, wherein said transducer comprises at least one thermocouple.
 8. The assembly of claim 7, wherein said adaptation to shut-down said combustion-powered heater is an adaptation wherein said thermocouple ceases holding open a normally-closed valve.
 9. The assembly of claim 8, wherein the temperature of the radiant surface is adapted to be less than the temperature limit during operation of the heater in an atmosphere comprising less than 18% oxygen by volume.
 10. A method of selectively shutting off a combustion-powered portable heater, comprising: providing a combustion-powered heater, said heater comprising a combustion site adapted to power said heater when in operation; engaging a target component with said combustion site in such a manner that said combustion site heats said target component when in operation; and operatively engaging a transducer with said target component, said transducer, adapted to measure the temperature of the target component, and adapted to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.
 11. The method of claim 10, wherein said heater is portable.
 12. The method of claim 11, wherein said heater is adapted to consume oxygen from air and propane fuel.
 13. The method of claim 12, wherein said target component comprises a burner output modifier.
 14. The method of claim 13, wherein said operatively engaging a transducer with said burner output modifier comprises embedding said transducer within said burner output modifier.
 15. The method of claim 14, wherein said burner output modifier comprises a radiant surface.
 16. The method of claim 15, wherein said transducer comprises at least one thermocouple.
 17. The method of claim 16, wherein said adaptation to shut-down said combustion-powered heater is an adaptation wherein said thermocouple ceases holding open a normally-closed valve.
 18. The method of claim 17, wherein said thermocouple ceases holding open a normally-closed valve during operation of said heater in an atmosphere comprising less than 18% oxygen by volume.
 19. An assembly comprising: a portable, combustion-powered heater comprising a combustion site adapted to power said heater, said heater adapted to consume oxygen from air and propane fuel; a radiant surface engaged with said combustion site; and at least one thermocouple embedded within said radiant surface, said at least one thermocouple, adapted to measure the temperature of the radiant surface, and adapted to cease holding open a normally-closed valve to shut-down said combustion-powered heater in response to a temperature measurement of less than a temperature limit.
 20. The assembly of claim 19, wherein the temperature of the radiant surface is adapted to be less than the temperature limit during operation of the heater in an atmosphere comprising less than 18% oxygen by volume. 